class Solution4 {

    boolean[][] vis;
    int ret, m, n;
    int[] dx = {0,0,1,-1};
    int[] dy = {1,-1,0,0};

    public int getMaximumGold(int[][] grid) {
        m = grid.length; n = grid[0].length;
        vis = new boolean[m][n];

        for(int i = 0; i < m; i++){
            for(int j = 0; j < n; j++){
                if(grid[i][j] != 0){
                    vis[i][j] = true;
                    dfs(grid, i, j, grid[i][j]);
                    vis[i][j] = false;
                }
            }
        }
        return ret;
    }

    public void dfs(int[][] grid, int i, int j, int path){       
        ret = Math.max(ret, path);

        for(int k = 0; k < 4; k++){
            int x = i + dx[k], y = j + dy[k];
            if(x >= 0 && x < m && y >= 0 && y < n && !vis[x][y] && grid[x][y] != 0){
                vis[x][y] = true;
                dfs(grid, x, y, path + grid[x][y]);
                vis[x][y] = false;                
            }
        } 
    }
}